Blend Door Actuator?

I am having problems with the blend door actuator. It seems to be a common issue in the 2007 Mustangs. I researched it, but here's my problem. I have no idea which part I need to replace. So I'm hoping someone here can help me out.

When I turn my car on, you get the clicking noise for about ten seconds and then it goes off. My defrost works perfectly fine, rear defrost as well. Cold air always works fine too. My problem is either when I switch from cold to hot, sometimes the air never changes and just stays cold. Or if I have the defrost on(heat) and want to switch it to the vents, sometimes it doesn't switch. Last night I had it on defrost and when I switched the control to the vents, the defrost stayed on.

So with that all said, O'Reilly Auto Parts seems to have a ton of options. I am told there's only three blend door actuators, so I'm confused how they have so many options. But, those options include: Air Inlet Door, Defrost Door, Panel Airflow, Recirculation mode door, and mode door actuator.

Now just me taking a guess here, I would say it's the Mode Door Actuator. That's a Motorcraft part listed on O'Reilly's site. But, I'm just not sure what all the others are. Could it be the defrost door? Defrost works fine front and back, but it sometimes doesn't switch between defrost and vent. Anyways, thanks for all help. Just trying to figure out what I need before I tear everything apart and fix the wrong thing

I would think that there would be a way during your teardown to test the sound to see where it is actually coming from. Additionally, if they are items that can be returned as unopened, you can get one of each and return the ones you dont replace. Just a thought.

I just had the same problem about a week ago except just no heat. Had to remove the blend door motor to get the part # for dealership.When installing the motor the gear can only slide in one way so you have to switch the temp. Control to make the gear spin.